I just looked at my race schedule and it looks like I may be pushing the life of my aluminum rods to get through the season.
But whats crazy is i have seen one motor with 20 passes break an aluminum rod and another motor go 200 passes and they remain perfectly healthy.

So i guess my question is what is the best way to treat the rods to get the most life out of them?
It looks like the biggest wear and tear on the rods is deceleration.Im hearing that power adders or compressive load are not a wear factor unless you over power the rod,then it will actually bend.Its when the piston and rod assembly get to tdc and then have to reverse direction,thats the rod killer.
I guess your aluminum rod manufacturer can give you a rough idea on how many runs you can get out of the rods by configuring crank stroke,component weight ie piston weight,the type of fastener your using and what rpm you are trapping at.
Im thinking that maybe in my burnout it may be helpfull to ease out of the throttle at the end of my burnout instead of lifting quickly.This may slow the decelaration of the rod a bit as well as shifting into neutral in the traps?I dont think shutting the motor completely off is whats best,especially with a powerglide transmission
Other than that maybe a bit of luck?

The biggest enemy of aluminum rods is improper warm ups. You can't start the engine, warm up the coolant, then go make a run. The entire engine needs to heat sink before making a run.

quote:

The biggest enemy of aluminum rods is improper warm ups. You can't start the engine, warm up the coolant, then go make a run. The entire engine needs to heat sink before making a run.

Another good tip,maybe pre heat the oil and warm the motor up.
But my issue is I am blown alky so she dosent build a lot of engine heat and I tow it up to the line and back.

have you seen wear on the top and bottom of bearings ,just a question to help my thought process.and if you had rod failure what did the bearing look like

I understand having the motor and oil up to good temperature before running. But I think you do not want to get the rods too hot. I work in aircraft and many years ago they used to heat up aluminum with blow dryer type heat gun to make it easier to work. Really did not take that much heat to make it softer and easier to bend. I would be willing to bet that high oil temperatures would shorten life of the rods.

The basic properties of aluminum is it expands faster and more than the steel crankshaft which changes the lubrication and tolerances. That is another reason I think heat should be more closely regulated with aluminum rods.

In the past many used to say that using motor to help slow car was hard on the rods and they suggested putting it up in neutral and coasting to stop. I personally do not see how that makes any noticeable difference or why but many believe that.

RPM, detonation and lack of lubrication are of course an issue to.

I'm using MGP rods. I just sent mine back for evaluation after 35 runs to check there condition and get an estimated life span at my power and RPM level. They completely disassemble and clean the rods, measure both small and large bore, check length, straightness etc compared to when they are new, polished them and reassemble, Called me and gave me a detailed report on there condition based on my power level, where there at and what they expect them to be at all FREE OF CHARGE. The only thing it cost me was shipping in both directions. Now that's what I call customer service.

also IMO most rods fail because of other reasons, spun or lock up bearing, rod bolt failure from improper stretching etc

Also everytime you rip the throttle driving the stripe is considered a run lol. Ripping the throttle is probably the worst thing you can do to a aluminum rod

quote:

RPM, detonation and lack of lubrication are of course an issue to.

if bearings dont give an indicator then other things are at play.i ( think) pistons will suffer from being in gear on shutdown as much as rods if that is an issue.at the speeds jenevet is running being in gear creates lots of drag.still not sure of how much of a problem it is.the bearings should show the issue either on top or bottom.mine ran ran all season and bearings were in excellent shape on teardown,after hearing response from jenevet i will giv my procedure.it wont change just would like to hear first

Having run aluminum rods for 30 plus years. I can tell you rod bolt failure is 90% of what causes damage.

Not revving motor when cold is one of my golden rules.Checking rod bolt for stretch every time its down is another. You do not have to heat motor.Just fire it up set shutoff part way and let it warm naturally. Not doing throttle snap that sounds cool as he11 and as much fun,helps too. You do not need fast response at swap of feet and not leaving from idle,so what do you really learn from it?

I found a fool proof method for getting aluminum connecting rods to survive, I took them out of the engine, placed them on the work bench and replaced them with steel rods.

After 35 years of waiting (and carefully watching) not one of the eight have broken (again).

Bob

quote:

Originally posted by RPROGAS:
I found a fool proof method for getting aluminum connecting rods to survive, I took them out of the engine, placed them on the work bench and replaced them with steel rods.

After 35 years of waiting (and carefully watching) not one of the eight have broken (again).

Bob

Mic Drop lolo

Ditto, is the aluminum rod a requirement?

quote:

Originally posted by TORQIN:
Ditto, is the aluminum rod a requirement?

Nothing is a requirement but in a supercharged high RPM engine they are highly recommended because they act as a shock absorber to help not beat the crap out of the crank. When was the last time you saw steel rods on a blown alky or nitro motor?

quote:

Originally posted by RPROGAS:
I found a fool proof method for getting aluminum connecting rods to survive, I took them out of the engine, placed them on the work bench and replaced them with steel rods.

After 35 years of waiting (and carefully watching) not one of the eight have broken



(again).

Bob

What’s the quote? ;
Bob knows.. I just could not resist..
It’s not a matter of if, it’s a matter of when and power level dictates stress as well as chips, burnouts and whomp whomp.. JMHO
Steel is great insurance.
Have no idea regarding supercharged engines..

rusty, bearings look like new so no issues there.everything is healthy right now just looking at the season and hoping I can get max life out of the rods.
and big steve is correct in these blown alky motors you need an aluminum rod to dampen the pounding on the crankshaft.

quote:

power level dictates stress as well

according to all the rod builders,if the rod is the correct one for your application,power will not affect the life of the rod.they say if you did over power the rod it will bend.
these are the factors they claim will affect rod life
component weight...which is the piston weight

crankshaft stroke

rod bolt quality

rpms turned

quote:

Originally posted by jenavet:
rusty, bearings look like new so no issues there.everything is healthy right now just looking at the season and hoping I can get max life out of the rods.
and big steve is correct in these blown alky motors you need an aluminum rod to dampen the pounding on the crankshaft.

If your engine is apart then why not send them back to the manufacture for inspection like I did? Might give you some piece of mind that there is no issues

Steve, so what did MGP end up telling you other than they were within spec?

I bought a set of MGP 3200 series for my hemi based on what the TA guys are running.
I'll never run mine as hard as they do, so I'm expecting to get a number of runs out of them.

Dave

quote:

Originally posted by Big Steve:

quote:

Originally posted by TORQIN:
Ditto, is the aluminum rod a requirement?

Nothing is a requirement but in a supercharged high RPM engine they are highly recommended because they act as a shock absorber to help not beat the crap out of the crank. When was the last time you saw steel rods on a blown alky or nitro motor?

Kind of thinking out loud here but aluminum rods are lighter and that may be why pro teams use them and they have the budget to change them out. On a 10,000 horsepower motor that gets new rods every 6 passes sure. But on anything less I would think the steel rods would be better and last longer. I wonder if any Top Alcohol Dragster teams have really tried steel rods? Or if it is just a bunch of well that is what everyone else does?
I to have always heard the aluminum rods act as a "Shock absorber" but I wonder how much they can really do with out bending and breaking? If that was the case why don't they make aluminum crankshafts? To my way of thinking steel is better material for both.
Another argument I have heard in favor of aluminum rods is if (when) you break a rod it does not destroy the block. From what I have seen they are just as bad. When you throw the rods out it just gets ugly.

I do know for most of us the steel rods last longer.
When performing an autopsy a close look at the bearings may be able to determine the cause of death.

I understand talking about shutting it off after a run coasting to a stop and ripping throttle etc. I just do not know how much difference it makes. I really do not know how we will ever know because there is so many other variables such as timing, fuel distribution, RPM, load etc.
Bolts are a weak spot on rods but seems to be more so on aluminum rods?

Not arguing here just throwing some questions out there to think about.

quote:

If your engine is apart then why not send them back to the manufacture for inspection like I did? Might give you some piece of mind that there is no issues

steve ive been averaging 80-100 passes on the rods in this application.when I had it apart 2 months ago I only had 30 passes on the rods.but now as I head to florida next week and look at the season,if I don't do well it puts me at about 100 passes.if I go rounds could be 10-20 more.
im going to call the manufacturer tomorrow and see what they say

Bruce,

I think the main reason which takes into account of "shock absorber", is detonation.

Good article here:
Aluminum vs Steel Rods

Same guy or family that owned GRP now owns MGP and has developed a few new ideas/materials, if there are such a thing.

Dave